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In the past two years, six separate meta-analyses have been published on the relationship between fish consumption and type 2 diabetes. The whole point of a meta-analysis, though, is to compile together the best studies done to date, and see what the overall balance of evidence shows. The fact that there are six different ones published recently highlights how open the question remains. One thread of consistency, though, was that fish consumers in the United States tended to be at greater risk for diabetes.
If you include Europe too, then fish-eaters appeared to have a 38% increased risk of diabetes. On a per-serving basis, that comes out to be about a 5% increase in risk for every serving of fish one has per week. To put that into perspective, a serving of red meat is associated with a 19% increase in risk—but, that’s per day. Just one serving a week of fish is 5%, so a serving a day would be like a 35% increase in risk—worse than red meat, but why?
Well, fish intake and omega-3 fats may increase type 2 diabetes risk by increasing blood sugar levels, as found in a review of the evidence commissioned by the U.S. government. An increase in blood sugars in diabetics given fish oil. Or, it may be because the omega-3s cause “oxidative stress.” A recent study found that the insulin-producing cells in the pancreas don’t appear to work as well in people who eat two or more servings of fish a week. Or, it may be because of the “environmental contaminants” that build up in fish.
It all started with Agent Orange. We sprayed twenty million gallons of the stuff on Vietnam, and some of it was contaminated with trace amounts of dioxins. Though the Red Cross there estimates a million Vietnamese were adversely affected, what about all the servicemen, the U.S. servicemen, who were exposed, spraying it across the countryside? Reports started showing up that veterans exposed to Agent Orange appeared to have higher diabetes rates than unexposed veterans—a link that’s now officially recognized.
These so-called “persistent organic pollutants…are mainly man-made [industrial] chemicals…, and…among the most hazardous compounds ever synthesized. [They] include…dioxins,…PCBs, and certain…chlorine-containing pesticides, [all of] which are highly resistant to [breaking down in the environment].”
“Initially described for their deleterious effect[s] on reproductive function” and their ability to cause cancer, “there is now [a] growing body of evidence showing that exposure to [these pollutants] leads to metabolic diseases,” such as diabetes. This is “a breakthrough that should require our greatest attention.”